Lubricating greases



i aten tecl June 8, 1948 2,442,828 LUBRICATING GREASES Herschel G.Smith, Wallingford, Mark L. Hill, Yeadon, and Carl Malcolm Peck,Havertown, Pa., assignors to Gulf Oil Corporation, Pittsburgh, Pa., acorporation of Pennsylvania No Drawing. Application April 1'7, 1946,Serial No. 662,928

4 Claims. (Cl. 252-40) This invention relates to novel lubricatinggreases and more particularly to block greases of spongy texture whichare especially useful for lubricating bearings that operate at hightemperatures since they are not rapidly consumed at high bearingtemperatures.

It is an object of this invention to produce block greases that are notrapidly consumed when they are used to lubricate bearings that areoperating at high temperatures. A further object is to manufacture blockgreases which are not rapidly consumed at high operating temperaturesand. which will also provide excellent lubrication for bearings that areoperating at lower temperatures. Other objects will appear hereinafter.

These objects are accomplished in accordance with the present inventionby making block greases which comprise a mineral oil thickened with amixture of sodium and calcium soaps which contain a suflicient amount ofthe saponification products of carnauba wax or ouricury wax and of asodium carbonate to decrease its rate of consumption at high bearingtemperatures. The amount of carnauba wax or ouricury wax used inpreparing these block greases may vary from 0.2 to 20 per cent by weightof the final product. Preferably the block greases of this inventioncomprise from about 70 per cent to about 85 per cent by weight of amineral oil which has been thickened to a grease with from about percent to about 25 per cent by Weight of a mixture of sodium and calciumsoaps and which also contains from about 0.2 per cent to about 2.5 percent by weight of carnauba wax in the form of its saponificationproducts and from about 0.2 per cent to about 0.4 per cent by weight ofexcess alkali in the form of a sodium carbonate.

The following examples illustrate but do not limit the invention. Allparts are given by weight except where otherwise noted.

Example I.To a pressure type grease kettle equipped with a mechanicalagitator and means of heating with steam were charged 17 parts of tallowand 4.1 parts of stearic acid which were melted and heated to l80 F.Then 8.51 parts of a 35.9 per cent caustic soda solution were added.Heat was applied and the temperature gradually raised to 200 F. withagitation; then 0.51 part of lime mixed in a slurry with 1 part of waterwas charged to the kettle. Heating and stirring were continued until atemperature of approximately 250 F. was attained and the soap stock wassubstantially dehydrated and appreciably thickened. At this point asolution of 2 parts carnauba wax dissolved in 2 parts of mineral oil at220 F. was added to the soap stock. superheated steam at a temperatureof 600 F. was admitted to the jacket of the kettle, and the temperatureof the kettle raised to 450 F. During this heating period 71.2 parts ofsolvent refined mineral oil having a viscosity of seconds SUV at 100 F.were added to the kettle at such a'rate as to keep the soap stocksufficiently soft to prevent overloading of the stirring mechanism. When450 F. temperature was reached, 0.4 part of'powdered sodium bicarbonatewas slowly added to the kettle and stirred into the grease for 15minutes. Then 0.03 part of a 35.9 per cent caustic soda solution wasslowly poured into the kettle. The temperature of the kettle wasmaintained at 450-460 F. for approximately 2 hours and then the greasewas drawn from the kettle into trays for cooling. The composition andinspection data on the block grease thus prepared is set forth in thefollowing table.

. Table I Block-type grease Composition: per cent by weight:

100 seconds SUV at 100 F.:

Solvent refined coastal oil 73.2 Calcium and sodium soaps of stearicacid and tallow 22.0 Excess compounding alkali or alkalis. 1.0 Glycerine(theoretical) 1.8 Carnauba wax 2.0 Inspection:

Melting point: (Hawxhurst) F 334 Dropping point F 358 Penetration, ASTMD2l7-44T-77 F.,

g., 5 sec.:

Unworked 57 Worked 198 Grease consumption test g./hr.: Temperature ofjournal:

Atmospheric temp 6 227 F 5 240 F 4 260 F 4 281 F 7 298 F 14 320 F 40 1The dropping point testis described on page 14 of ASTM Standards onPetroleum Products and Lubricants dated September, 1937.

2 The grease consumption test was performed in an apparatus described inU. S. Patent No. 2,385,656, issued September 25, 1945, to H. G. Smith.The testsample was a block measuring 3% inches by 3 inches by 4 inchesand weighing about 700 grams. The journal was a faced cylinder 8 inchesin diameter which was re volved 267 times per minute which gave aperipheral speed of 594 feet per minute to the journal.

Table II .-Stabzlzzed block greases 22% Soap 17% Soap 12% Soap ContentContent Content Grease Grease Grease Composition, per cent by Wt:

100 Seconds SUV at 100 F.-

Solvent refined Mid-Contincut oil 73.7 79.3 84T95' Calcium and sodiumsoaps of tallow and stearic acid 22. 17.0 12.0 Excess compounding alkalior kalis 1.0 0.8 0.55 Glycerine (Theoretical) 1. 8 1. 4 1. 0 Carnaubawax 1. 1. 5 1. 5 Inspection:

Melting Point (Hawxhurst), R 340 332 314 Dropping Point, F 358 359 345Penetration, ASTM D 7 14T 77 F., 150 G., 5 Sea:

Unworked 59 65 82 Worked 180 206 229 Grease Consumption Test,

G./Hr.-

Temperature of Journal:

Atmospheric Temp 7 1 3 227 F 5 3 14 4 3 7 4 5 3 7 10 22 27 10 44 102 1946 Example III.-The following table illustrates the fact that a greasewhich is prepared without the inclusion ofsodium bicarbonate in itsmakeup is consumed far more rapidly than a block grease to which sodiumbicarbonate has been added during its preparation. The greases describedin the following table were both prepared in accordance with the generalprocedure described above in Example I except that in the preparation ofthe grease without NaHCOs the step of adding sodium bicarbonate wasomitted.

Table Uri-Block greases The dropping points and grease consumption datagiven in Tables II and III are determined in accordance with theprocedures indicated in the footnotes to Table I.

Example IV.A block grease having a. spongy texture which contained '1.5per cent by weight of ouricury wax and 22 percent by weight of calciumand sodium soaps in its make-up was prepared in accordance with thegeneral procedure which is detailed above in Example I. The

composition and inspection data on this block grease are set forth inthe following table.

Table IV Composition: per cent by wt.:

seconds SUV at 100 F. solvent refined Mid-Continent oil 74.1 Calcium andsodium soaps of stearic acid and tallow 22.0 Excess compounding alkalior alkalis 1.0 Glycerine (theoretical) 1.4 Ouricury wax 1.5 Inspection:

Melting point: (Hawxhurst) "F 332 Dropping point: F. 360 'Penetration,ASTM D217-44 T77 F.,

g.,-5 sec.:

Unworked 58 Worked Grease consumption test: g./hr.:

Temperature of journal:

260 F. 9 281 F. 15 298 F. 24

The dropping point and grease consumption data iven in the above tableare determined in accordance with the procedures outlined in thefootnotes to Table I.

In the preparation of these block greases any suitable lubricating oilmay be used such as solvent refined coastal and midcontinent oils havinviscosities ranging from 100 to 150 seconds SUV at 100 F.

The sodium and. calcium soaps used in thickening theseoils to greasesmay be prepared fromany suitable fats or higher fatty acids such astallow, stearic acid or hydrogenated fish oil fatty acids. Any suitablemixture of these fats and and fatty acids may also be employed.

In the presence of excess alkali camauba wax issaponified to form asoapof the carnauba wax acids and the higher alcohols which are found incarnauba wax. Neither the soap nor the higher alcohols after beingformed are removed during the later stages of grease manufacture.

In order that the greases of the present invention will not be consumedrapidly at high bearing temperatures it is also .necessary to include intheir composition a small amount of excess alkali in the formv ofasodium carbonate. As shown above in Example Ithis excess alkali in theform of a sodium carbonate may be introduced into the grease by addingsodium bicarbonate to the batch during the manufacture of the grease.Alternatively, gaseous carbon dioxide may be used in place ofsodium'bicarbonate. In this alternate procedure the gaseous carbondioxide is contacted with the melted grease for the length of timenecessary to givethe desired results during the finishing process ofthe, grease. Whether the carbonate in the g-rease'exists in the form ofsodium carbonate .or sodium bicarbonate is not Precisely known and,therefore, we refer to it as excess alkali in the form of .a sodiumcarbonate.

The stages of processing at which the carnauba wax and sodiumbicarbonate may be added to the grease batch are variable. We have foundit desirable to add the sodium bicarbonate at a maximum temperature.After the grease containing all the other ingredients has been melted,the water of reaction liberated from the addition of the sodiumbicarbonate and subsequent minor portion oficaustic soda solutionrapidly evaporates without causing an excessive or persistent emulsion.For this reason, it is likewise desirable to add the carnauba wax at anearly stage of the process, as described above in Ex ample I; however,it also may be charged with the fats and/ or fatty acids used for thesoap formation.

We prefer in preparing our new block greases to use from 14 per cent to22 per cent by weight of a mixture of sodium and calcium soaps made froma mixture of .tallow and stearic acid and from 1.5 per cent to 2.5 percent by weight of carnauba wax and to employ sodium bicarbonate tointroduce excess alkali in the form of a sodium carbonate. The blockgreases of the present invention which have the most desirable physicalproperties have compositions falling within the following range:

Component er qveit by Greases prepared according to the presentinvention have improved consumption characteristics and give excellentlubrication. Most of these greases lubricate bearings at 320 F. withmoderate grease consumption; however, they also give excellentlubrication at lower temperatures with very low consumption. Thesegreases have a spongy texture. We do not limit the carnauba wax contentof these greases to 0.2-2.5 per cent since we are able to make improvedgreases containing from 0.2 per cent to 20 per cent of carnauba wax.

The block greases of the present invention are particularly useful in.the lubrication of journals and other bearings operating at hightemperatures such as the hot roll bearings of machinery used in themanufacture of paper and cement. These block greases afiord excellentlubrication to bearings operating at high temperatures and are notconsumed at an excessive rate while they are lubricating such hotbearings.

By the addition of from 1 per cent to 2 per cent of carnauba wax we havebeen able to prepare a block grease containing but 12 per cent of amixture of sodium and calcium soaps which has superior physicalproperties to a block grease that has been prepared in a similar mannerand which contains 22 per cent of a mixture of sodium and calcium soapsbut no carnauba wax. The block grease containing 12 per cent of soap andfrom 1 per cent to 2 per cent of carnauba wax will lubricate bearingsoperating at high temperatures better than a grease similarly preparedwhich has a sodium and calcium soap content of 22 per cent but whichcontains no carnauba wax. The grease which contains 22 per cent ofsodium and calcium soaps but no carnauba Wax will not lubricate bearingsthat operate at temperatures above 240 F. without being excessivelyconsumed. On the other hand, a block grease prepared in accordance withour invention which contains 12 per cent of sodium and calcium soaps and1.5 per cent of carnauba wax will lubricate bearings operating at 320 F.without being excessively consumed.

Resort may be had to such modifications and variations as fall withinthe spirit of the invention and the scope of the appended claims.

What we claim is:

1. A block grease of spongy texture which is not rapidly consumed athigh bearing temperatures which comprises a major amount of a soda limebase block grease, and minor amounts, suffi cient. to decrease the rateof consumption of said block grease at high bearing temperatures, of thealkali saponification products of a wax selected from the groupconsisting of carnauba wax and ouricury wax, and of excess alkali in theform of a sodium carbonate, the amount of said wax in the form of itsalkali saponification products being from 0.2 to 20 per cent by weight,and the amount of said excess alkali being from about 0.2 to about 0.4per cent by weight.

2. The grease of claim 1, wherein the wax is carnauba wax.

3. A block grease of spongy texture which is not rapidly consumed athigh bearing temperatures which comprises from about per cent to aboutper cent by weight of a mineral oil which has been thickened to a greasewith from about 10 per cent to about 25 per cent by weight of a mixtureof sodium-and calcium soaps and which also contains from about 0.2 percent to about 2.5 per cent by weight of carnauba wax in the form of itsalkali saponification products and from about 0.2 per cent to about 0.4per cent by weight of excess alkali in the form of a sodium carbonate.

4. The grease of claim 3, wherein the alkali saponification products ofthe carnauba wax include the sodium soaps of the carnauba wax acids andthe carnauba Wax alcoh'ols.

HERSCHEL G. SMITH. MARK L. HILL. CARL MALCOLM PECK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 26,693 McMunn Jan. 3, 18601,599,854 Van Gundy Sept. 14, 1926 2,148,292 Francis Feb. 21, 19392,197,263 Carmichael Apr. 16, 1940 2,321,384 Hemker June 8, 1943 OTHERREFERENCES Lubricating Greases, Klemgard, page 587, published by theReinhold Publishing Corp, 1937, New York, N. Y.

